Cutter bit holder



April 17, 19,62 H. A. DEvlNE ET AL 3,030,088

El .lllIlll/f ummm NNNNNNN RS 3,030,038 t CUTTER BET HLDER Hamid AaronDevine and Asa Lloyd McLaughlin, Carlsbad, N. Mex., assignors to PotashCompany oi America, Qarlsbarl, N. Mex., a corporation ot Coiorado FiledDec. 22, 1958, Ser. No. 782,049 6 Claims. (Cl. 262-33 This inventionrelates to cutter bit holders, and more particularly bit lfastenerassemblies which are arranged to be mounted on continuous miningmachines, and the like, utilizing rotary drums, moving chains, and thesimilar moving mechanisms which carry cutter bits in a disintegratingaction against ore in place.

There are diierent types of mining machines operating in the miningindustry which utilize a removal cutter -bit mounted on a holder whichis secured to a moving means, such as the links of a cutter chain, arotary drum and the like. Cutter -bits with narrow shanks are placed inthe holders and held in position for an attack on the ore face. Thecutter bits themselves may take a variety of shapes but lthey allgenerally include a shank for securing in the holder and a hardened tipwhich is the cutting surface. ln such mining machines, the cutter bitsmove at a relatively high velocity and the impact of the cutter bitagainst the ore face is extremely heavy. While the impact forces areheavy while the cutter bit is in contact with the ore face, the force isexerted by the shoulder of 'the cutter bit against the body of the bitholder and it is only necessary to retain the bit in its recess while itis not in engagement with the Ore face to prevent its loss due tocentrifugal force.

ln mechanical mining operations the dust and `lit produced by theoperation of the machine is extremely heavy and penetrating. The dustsettles and packs in crevices and voids in and around all mechanism thatif sufficient dust accumulates in the socket around the holdermechanism, it prevents free action of the holder mechanism which makesit difficult or impossible to insert and withdraw the bits.

Many different types of holders have been proposed for cutter bits whichinclude simple set screws through elaborate spring and plungercombinations. While some of these work satisfactorily for a period oftime, the dust soon accumulates in voids lling and packing the same andpreventing correct operation of the cutter bits. Also, the assembly anddisassembly ot these with the holder is diilicult and time consuming.

According to the present invention we have provided a simplied andhighly effective cutter bit fastener assembly which is essentiallyself-cleaning thus preventing Ithe accumulation of dust and grit. rthecutter bit fastener assembly, furthermore, provides a simplified andhighly effective means for replacing worn cutter bits, so that machinedown time for cutter bit replacement is substantially reduced, and incertain instances it is reduced to about a fourth of the time normallynecessary. The simplied cutter bit holder assembly is less expensive tomake than other quick change bit holders, and it is arranged to replacestandard set screws without modiiication of the cutter mounts.

It is an important object of the invention to provide a simplilied andhighly eifective mining machine spring loaded, cutter bit fastenerassembly.

It is a further object of the invention to provide a mining machinecutter bit fastener assembly which may be used in unmodiied standardcutter bit mounts whereby the fastener assembly of the invention isinterchangeable with standard set screws.

A further object of the invention is to provide a simpliiied cutter bitfastener assembly which is essentially self-cleaning under the action ofthe cutter bit.

w Patented Apr. 17, 1962 A still further object of the invention is toprovide a cutter bit fastener assembly which reduces the time and eiiortnecessary to replace cutter bits in the mount, and the replacement ofsuch cutter bits is simply and easily accomplished with simple tools.

A still further object of the invention is to provide a simpliiiedcutter bit fastener assembly which is completely replaceable with a setscrew.

These and other objects and advantages of the inven- -tion may bereadily ascertained by referring to the following description andappended illustrations in which:

FIG. 1 is a side elevational View, in partial section, of a cutter bitfastener assembly and a cutter bit mount according to the invention;

FIG. 2 is an end elevation of the device of FIG. 1; and

FiG. 3 is an enlarged detail of the fastener assembly of PEG. 1.

In the device illustrated, a cutter bit 1 is arranged to be mounted in arecess 2 in a cutter bit mount 3. The cutter bit mount may be any shapesuitable for mounting on a movable disintegrating member, partiallyshown at 4. in one form, the cutter bit mount 3 includes a body 16supported on legs 18 and 19. A threaded recess 5 extends from a side ofthe body 16 into the recess 2. The disintegrating member may be a chain,drum or the like, and in common practice the mount 3 is welded onto ythemoving member 4.

Threaded into the threaded bore 5 is a set screw 6 which has a squarehead 7 and an internal bore 8 terminating in an exterior opening 17. Aportion 9 of the bore 8 adjacent the head 7 is threaded. A hexagonal jamnut lll is mounted on external threads 11 of the set vscrew 6, and thejam nut is arranged to releasably secure the set screw 6 in position inthe bore 5. A helical or coil spring '12 is threadedly engaged with lthethreads 9 of the set screw 6. The spring is slightly compressed as it isengaged with the threads so that it has a snug fit and is securely heldtherein by the engagement. A round end plunger 14 is threadedly engagedby means of threads i5 with the opposite end of vthe coil spring i2. Theplunger 14 is thus arranged for reciprocable movement in the bore 8 andis retained therein by the spring. The rounded end extends beyond theinner end `of set screw 6.

The cutter bit 1 as illustrated includes a head portion 2li whichterminates at its upper end in a hardened insert 21 which is the actualcutting member, and a bearing shoulder 22 at the lower end. The head 2t?is attached to a shank portion 23 which is arranged to be inserted iniothe recess 2 in the mount. An indentation 24 in the rear portion ofshank is in alignment with the bore 5 when shoulder 22 is seated onsurface 3a. ln this position the end of the plunger ltd is forciblyengaged with the shank, but is releasable since the plunger may bedepressed out of the recess. The shank 23, also, includes a lower slopedsurface 26, which is cut away from the lower corner of the rear part ofthe shank, to permit the cutter to be inserted into the slot and rideover and depress the plunger i4 during insertion thereof.

In one common form of mining machine a set screw is mounted in bore 5and is forcibly seated on the cutter bit shank for holding same in therecess 2. Obviously, the cutter can only be inserted or withdrawn bybacking up the set screw to permit the travel of the cutter bit into andout of the recess 2. The cutter bit is held by tightening the set screwto hold the bit in place in the recess.

The fastening assembly of the invention, which is a set screw with acontained plunger, may replace the normal set screw without modiicationof the mount. When in position in the mount, the plunger 14 forciblyrests in the indentation 24 of the cutter bit. The spring loaded plungerpermits the cutter to rock or move in the recess during cutting action.Movement of the bit causes movement of the plunger to prevent a build upof dust and grit in the set screw bore and in and around the springtherein. The open end 17 of the set screw 6 permits a free passage ofdust and grit, and the piston-like action of the plunger i4 keeps boreclear and prevents packing of the dust and grit therein.

The cutter fastener assembly 3 is illustrated as an essentiallycylindrical upper body 16 terminating in lower legs 18 and t9. With thisarrangement a space is left between Vthe legs and the body portion intowhich the lower end f the cutter bit shank extends. This space permitsthe use of a pry tool for prying out the cutter bit. Since the cutterbit is held under spring load in the recess 2, a pry tool such as ascrew driver or other small implement is merely inserted under the endof the cutter and a quick pry pops the cutter out of the recess. Thecutter is easily assembled into the recess by merely pushing it or insome instances tapping it slightly to depress the plunger and to permitthe cutter to move into position in the recess.

The indentation 24 is shown as a three-sided indentation, it is obvious,however, that this may be any type of indentation to accommodate therounded end of the plunger 14 for holding the cutter in position in themount. 'I'he sloped sides of the preferred form of recess aid in removalof the bit Since the plunger will ride up the sloped sides and bedepressed permitting withdrawal of the bit.

The modification illustrated shows a preferred form of A closed end onthe outer end of the bore may be desirable under certain conditions.However, under ordinary conditions, the open end is the preferable formsince the great amount of dust and grit which is produced by the use ofthe mining machine is easily removed through the open end of the bore bythe piston action of the plunger.

While the invention has been illustrated by reference to specificembodiments, there is no intent to limitthe -a set screw with boreextending completely therethrough.

scope or the spirit of the invention to the precise details p so setforth. For example, the set screw is shown with a square head 7 and issecured by a hex jam nut 10. This, however, may be easily modified toprovide a standard hex head on the set screw. The set screw may, also,be a standard mild steel bolt, or other common bolt, drilled and tappedto accommodate the spring and plunger. Further, the jam nut may bereplaced by any common holding means to lock the bolt or set screw inposition for positioning the plunger. For simplicity and ease ofmanufacture and assembling, the use of the Spring threaded onto theplunger 14 and threaded into the bolt is a preferred form. Other meansof attachment may be utilized where replaceability is not a factor. Thusthe spring may be welded or otherwise securely fastened to the plunger14 and similarly fastened in the set screw. Other modifications mayoccur to those skilled in the art as obvious equivalents and such areintended to be included in the scope and spirit of the appended claims.

We claim:

1. The combination of a cutter bit mount fixed on a movable oredisintegrating member and having a recess for holding the shank of acutter bit, there being an internally threaded bore extending from anend of said mount into said recess substantially perpendicular to thelengthwise axis of a held cutter bit and in alignment with anindentation on the shank of said bit facing the bore, `a tubular memberhaving an externally threaded shank portion engaged with the threads ofsaid bore and terminating at an outer end, the passage in said tubularmember having a threaded portion at least adjacent its outer end, aplunger reciprocably mounted in said passage and having an end extendingbeyond said shank portion, the inner end of said plunger being connectedto a coil spring intermediate the ends of said passage and extendingrearwardly therefrom a substantial distance through said passage, theopposite end of said spring being in threaded engagement with thethreads of said passage in said tubular member providing an openingthrough said tubular member opposite said plunger, and means forremovably securing said member in said mount in position for forcefulengagement of said plunger with the indentation on said shank of thebit.

2. A cutter bit fastener assembly comprising a bolt including a headportion arranged to be disposed outside of a bore in which said bolt ismounted, an internal bore extending through said bolt and head portion,and the body of said bolt being arranged for releasably securing thesame in a mount; a plunger mounted for reciprocal movement in said boreand having a portion normally extending beyond said body; and a springheld at one end against outward movement from the bore through said headportion and arranged to maintain said bore open, said spring beingreleasably secured at its opposite end on a rear portion of said plungerintermediate the ends of said internal bore to force the plunger towardits normal extended position.

3. A cutter bit fastener assembly comprising a bolt including a headportion arranged to be disposed outside of a mount in which said bolt ismounted, an internal bore extending through said bolt and head portionand partially threaded adjacent said head portion, and the body of saidbolt being arranged for releasably securing the same in said mount; aplunger having a threaded inner portion mounted for reciprocal movementin said bore and having a portion normally extending beyond said body;and a helical spring threaded in said internal bore and arranged tomaintain said bore open at the head portion end, said spring beingthreaded to Said plunger intermediate the ends of said internal bore andarranged to force said plunger toward its normal extended position.

4. The combination of a cutter bit mount fixed on a movable oredisintegrating member and having a recess for holding the shank of acutter bit, said mount having a surface adjacent said recess arranged asa shoulder for butting relation with an external bearing shoulder on acutter bit mounted in said recess and having a passage extending from anend of said mount in said recess substantially perpendicular to thelengthwise axis of a held cutter bit and in general alignment with anindentation on the shank of a bit facing said passage, of a boltassembly having a shank arranged for telescoping engagement in saidpassage and terminating at its outer end in a head portion, said bolthaving a bore extending through the shank and said head portion, aplunger reciprocally mounted in said bore and having one end normallyextending beyond said shank in position to contact an indentation on acarried cutter bit, a coil spring disposed in said passage bearingagainst said plunger at one end intermediate the ends of said bore andheld in said bore against outward movement through the head portion atits other end in position to maintain said bore open through saidportion, and means for releasably securing said bolt in engagement withthe mount whereby to maintain the plunger in forceful engagement withthe indentation of a carried cutter bit.

5. The combination with a cutter bit for mining operations having ashank portion fitted in a socket, of a plunger assembly mounted in athreaded opening extend'- ing into said socket at substantially rightangles to the lengthwise axis of said shank, said plunger assemblycomprising an externally threaded bolt held in said opening and havingan internal open-ended bore extending throughout its length, a plungermember disposed in the forward end of said bore with a portion arrangedfor movement into and out of engagement with said shank, a coil springmounted on the rear end of said plunger and extending rearwardlytherefrom through a major portion of said bore to provide a passage ofsubstantial diameter for relief of dust consituents moving through saidsocket, and means bearing against the rearward end of said spring withinsaid bore so as to limit movement of the spring therein.

6. A cutter bit fastener assembly comprising a bolt including a headportion arranged to be disposed outside of a passage in which said boltis mounted, there being a continuous and unobstructed bore ofsubstantially uniform diameter extending throughout said bolt and headportion from one end to the other, means on said bolt for holding thesame in said passage means mounted for reciprocal movement at theforward end of said bolt bore and having a bit-engaging portion normallyextending outside of said bolt bore,'and a second resilient portioninterconnected therewith and disposed intermediate the ends of said boltbore, said resilient portion extending a substantial distance throughsaid bore from its interconnection With said bit-engaging portion, andmeans adjacent the rear end of said bore for preventing outward movementof said resilient portion and to maintain it under compression when saidbit-engaging portion is in engagement with the shank of a cutter bit,said resilient 6 member forming a continuous and unobstructed passage ofsubstantially uniform diameter within said bore providing a substantialoutlet from said passage for unobstructed free outow and discharge ofdust and line material from said assembly. A

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